City Air Quality Monitors Worked: Elevated Hexavalent Chromium Levels Detected, Watching for Pattern

Following routine weekly air quality testing on Saturday, December 2, 2023, the City of Paramount was made aware of elevated levels of hexavalent chromium detected in two locations: the monitor at 15701 Minnesota measured a reading of 6.807 nanograms per cubic meter (ng/m3) and the monitor at Gaines School measured a reading of 1.502 ng/m3.

After South Coast Air Quality Management District’s (SCAQMD) monitoring program ended in 2021, Paramount’s City-driven air quality monitoring program became the first of its kind and demonstrates the City’s dutiful resolve to safeguard air quality in its community.

SCAQMD has stated that concerns are raised if there are readings above 1.0 ng/m3 over three consecutive samplings. Any readings below that level are considered relatively normal “background” levels.

“Singular and seemingly random spikes in hexavalent chromium levels may periodically occur with little cause for alarm,” said Randall Baxter of Trinity Consultants, the environmental consultant responsible for air quality monitoring in Paramount. “We are most interested in watching the air quality readings in the coming weeks to evaluate for any trends that may be of concern.”

The City immediately reported these findings to SCAQMD for their awareness and guidance. In partnership with the City, Trinity Consultants will continue to diligently monitor the results of incoming weekly air quality tests. The City will respond swiftly in partnership with SCAQMD should further action need to be taken. The next test results are expected to be made available to the public by the week of December 18.

“The City of Paramount remains dedicated to transparency in all air quality matters,” said Paramount Mayor Isabel Aguayo. “The City’s network of air monitors have proven pivotal in our mission to detect these abnormalities so that we may report them to the regulatory authorities and keep our residents safe.”

As reported at the beginning of this year, hexavalent chromium levels have remained low, at an average of approximately 0.030 ng/m3. Air monitoring around school locations showed the lowest concentrations measured.

To learn more about air quality monitoring and view previous testing results, visit:

Update (2/5/2024)

15701 Minnesota
As of the air quality monitor reading on January 1, 2024, 15701 Minnesota has had five consecutive readings below 1.0 ng/m3. This pattern indicates that the December 2, 2023, spike was an isolated event and not a cause for concern. As a reminder, South Coast Air Quality Management District (SCAQMD) has stated that concerns would be raised if there are readings above 1.0 ng/m3 over three consecutive samplings. Per our standard process, we will continue to test and monitor air quality at this site.

Gaines Elementary School
The Gaines Elementary School air quality monitoring location has seen additional spiked readings since the beginning of December 2023, none of which were in a consecutive pattern. The first elevated reading occurred on December 2, 2023, at 1.502 ng/m3 and the second elevated reading occurred on December 20, 2023, at 1.205 ng/m3. Although these elevated readings did not occur in a consecutive pattern, the City of Paramount has elected to rent an air monitor for additional coverage of the area to better understand where these spikes are coming from and why they’re occurring. The additional monitor will be stationed on the east side of Garfield just south of Jackson beginning on January 24. We will continue to monitor this site closely for any emerging patterns and provide updates on this page. Any identifiable origins for the elevated readings will be immediately shared with the AQMD as the regulatory authorities for further investigation.

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